FIELD
[0001] The present disclosure relates to a respirator attachment component and to a respiratory
protection mask comprising such a respirator attachment component.
BACKGROUND
[0002] Respirators provide respiratory protection from airborne substances with filtering
processes and/or otherwise facilitating access to clean air. One characteristic of
these devices is the seal that is formed between the user and other functional components
of the respirator and the seal that is formed between the functional components and
structural components of the respirator.
[0003] One design consideration with these respirators is the air-tight fastening of an
inhalation air source component, an exhalation component and/or speaking diaphragm
to the structural component(s) of the respirator. This air-tight seal often requires
a separate gasket and/or mechanical seal that adds complexity and cost to the respirator
design.
US 6,298,849 discloses a respirator mask, including a body member of a thin, rigid plastic material
and having an inner surface conforming to a face of a user, the body member including
an inner surface and at least one opening to receive a filter cartridge, a first over-molded
member, formed of a flexible, rubber-like material and over-molded on the inner surface
of the body member to form an over-molded inner surface to fit and seal upon a face
of a user, a second over-molded member formed of a flexible rubber-like material and
over-molded within the at least one opening for receiving a filter cartridge and with
the second over-molded member, including at least one flange member extending inwardly
around the cartridge opening and flexible from a first position to seal to a cartridge
member to a second position to allow the cartridge member to pass through and then
return to the first position to lock the cartridge member within the cartridge opening.
US 2005/109343 discloses a facepiece insert that has a fluid communication component non-integrally
joined to a supporting portion, whereie the insert can be made by (a) providing at
least one supporting portion of a facepiece insert; (b) providing at least one fluid
communication component separately from the supporting portion of the facepiece insert;
and (c) securing the at least one fluid communication component to the at least one
supporting portion.
[0004] WO 2007/009182 discloses a respiratory mask for administering a breathable gas to a patient, the
respiratory mask comprising a first component, a sealing cushion, formed from a flexible
material and a second component, a frame, formed from a material that is more rigid
than the flexible material, wherein the first component is formed onto the second
component by an over-molding process.
BRIEF SUMMARY
[0005] The present disclosure relates to a respirator attachment component as in claim 1.
This disclosure further relates to a respiratory protection mask as in claim 2 that
includes a respirator attachment component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention may be more completely understood in consideration of the following
detailed description of various embodiments of the invention in connection with the
accompanying drawings, in which:
FIG. 1 is a perspective view of an illustrative full face respirator;
FIG. 2 is an exploded perspective view of an illustrative full face respirator;
FIG. 3 is a perspective view of an respirator attachment component;
FIG. 4 is a cross-section perspective view of the respirator attachment component illustrated
in FIG. 3;
FIG. 5 is a perspective view of an respirator attachment component;
FIG. 6 is a cross-section perspective view or me respirator attachment component illustrated
in FIG. 5;
FIG. 7 is a perspective view of an respirator attachment component; and
FIG. 8 is a cross-section perspective view of the respirator attachment component illustrated
in FIG. 7.
[0007] The figures are not necessarily to scale. Like numbers used in the figures refer
to like components. However, it will be understood that the use of a number to refer
to a component in a given figure is not intended to limit the component in another
figure labeled with the same number.
DETAILED DESCRIPTION
[0008] In the following description, reference is made to the accompanying drawings that
form a part hereof, and in which are shown by way of illustration several specific
embodiments. It is to be understood that other embodiments are contemplated and may
be made without departing from the scope of the present invention. The following detailed
description, therefore, is not to be taken in a limiting sense.
[0009] All scientific and technical terms used herein have meanings commonly used in the
art unless otherwise specified. The definitions provided herein are to facilitate
understanding of certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0010] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical
properties used in the specification and claims are to be understood as being modified
in all instances by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the foregoing specification and attached claims
are approximations that can vary depending upon the desired properties sought to be
obtained by those skilled in the art utilizing the teachings disclosed herein.
[0011] The recitation or numerical ranges by endpoints includes an numbers subsumed within
that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range
within that range.
[0012] As used in this specification and the appended claims, the singular forms "a", "an",
and "the" encompass embodiments having plural referents, unless the content clearly
dictates otherwise. As used in this specification and the appended claims, the term
"or" is generally employed in its sense including "and/or" unless the content clearly
dictates otherwise.
[0013] The term "respirator" means a personal respiratory protection device that is worn
by a person to filter air before the air enters the person's respiratory system. This
term includes full face respirators, half mask respirators, supplied air hoods, powered
air purifying respirators, and self contained breathing apparatus.
[0014] The phrase "full face respirator" means a respirator that is worn over a person's
nose, mouth, and eyes.
[0015] The present disclosure relates to a respirator attachment component and particularly
to a respirator attachment component with a molded thermoset elastomeric seal. This
disclosure further relates to a respirator that includes a respirator attachment component
with a molded thermoset elastomeric seal. This molded thermoset elastomeric seal is
chemically bonded to at least one or two surfaces of the attachment component. In
many embodiments, the silicone seal element penetrates through the respirator attachment
component body. These respirator attachment components have a robust bond between
the silicone seal element and the polymeric rigid attachment component. While the
present invention is not so limited, an appreciation of various aspects of the invention
will be gained through a discussion of the examples provided below.
[0016] The respirator attachment component overmolded thermoset elastomeric seal provides
a sealing element that is integrally bonded with the attachment component body. This
construction has been found to enhance the durability of the seal and prevent debris
from being interposed between the attachment component body and the thermoset elastomeric
seal. This integral construction also reduces the number of assembly parts and part
size variability. The overmolded thermoset elastomeric seal materials described herein
also do not require that the attachment component body be primed in order for the
thermoset elastomeric seal to be chemically attached to the attachment component body.
[0017] FIG. 1 is a perspective view of an illustrative full face respirator
10.
FIG. 2 is an exploded perspective view of the illustrative full face respirator
10. This respiratory protection mask
10 includes a polymeric rigid facepiece body
11, face shield
11, or lens
11 attached to a number of respirator attachment components including, for example,
one or more inhalation valves
18 with an optional chemical or particulate filtration cartridge (not shown) connected
to one or more of the inhalation valves
18, one or more exhalation valves
16, one or more speaking diaphragms
14, and/or one or more headstraps or straps
34 configured to secure the respirator
10 to a user's head. A valve cover
8 is disposed over the exhalation valves
16 and speaking diaphragm
14.
[0018] The respirator
10 includes a compliant face contacting member
9 that is compliantly fashioned to allow the respirator body or face shield
11 to be comfortably supported over a person's nose and mouth. The illustrated respirator
10 includes two cheek openings
12 and two nasal openings
13.
FIG. 1 illustrates two cheek openings
12 where one cheek opening does not contain a respirator attachment component and one
cheek opening includes an inhalation valve
18.
FIG. 2 illustrates an inhalation valve
18 in cheek opening
12.
[0019] Respirator attachment components
14,
16, and
18 are disposed within or fixed to the openings
12 and
13 by any useful method such as, for example, a bayonet attachment system. A bayonet
attachment system is configured for attaching two portions together, where the two
portions include elements other than mainly threads such that the two portions are
attached by inserting one portion at least partially within the other portion and
rotating one portion relative to the other portion so that the two portions can be
joined without multiple turns.
[0020] While
FIG. 1 and
FIG. 2 illustrate a respiratory protection mask
10 having one or two cheek inhalation valves
18, and a nasal exhalation valve
16, and a nasal speaking diaphragm
14, any useful respiratory protection configuration is possible. For example, the respiratory
protection mask
10 can have a single inhalation valve attached to a chemical or particulate nitration
cartridge or clean air supply, and one or two exhalation valves or one or more speaking
diaphragms, as desired.
[0021] FIG. 3 is a perspective view of an illustrative inhalation valve
18 and
FIG. 4 is a cross-section perspective view of the illustrative inhalation valve
18 illustrated in
FIG. 3. The inhalation valve
18 includes a polymeric rigid respirator attachment body portion
20 having a first surface
21 and a second surface
22. A silicone sealing element
23 is chemically bonded to the first surface
21 and the second surface
22.
[0022] The silicone sealing element
23 can be formed by overmolding a thermosetting silicone material onto a thermoplastic
polymeric rigid respirator attachment body portion
20. The thermosetting silicone material chemically bonds (i.e., adhesive bonding or
covalent bonding) directly onto to the thermoplastic polymeric rigid respirator attachment
body portion
20 first surface
21 and the second surface
22.
[0023] The terms "chemical bonding or chemically bonded" refer to physical processes responsible
for the attractive interactions between atoms and molecules and includes covalent
and ionic bonds, as well as hydrogen and van der Waal's bonds and can often depend
on available functional groups on the polymeric rigid respirator attachment body portion
surface and their reactivity with the thermosetting silicone material. In many embodiments,
the thermosetting silicone material is selected so that pretreatment of the thermoplastic
polymeric rigid respirator attachment body portion is not necessary. In other words,
the thermosetting silicone material is self-adhesive with the thermoplastic polymeric
rigid respirator attachment body portion. The thermosetting silicone material is often
heated to cure the thermosetting silicone material during the overmolding process
to a temperature sufficient to cure the thermosetting silicone material but less than
a glass transition temperature of the thermoplastic polymeric rigid respirator attachment
body portion.
[0024] As shown in the Examples below, the level of chemical bonding can be determined by
the average force to failure test method. In many embodiments, the average force to
failure is 25 N or greater, 50 N or greater, or 100 N or greater, or 150 N or greater,
or 200 N or greater, or 300 N or greater.
[0025] The thermoplastic polymeric rigid respirator attachment body portion
20 can be formed of any useful thermoplastic material. In many embodiments, the thermoplastic
polymeric rigid respirator attachment body portion
20 is formed of a polyamide (e.g., nylon), a polycarbonate, polybutylene-terephthalate,
polyphenyl oxide, polyphthalamide, or mixtures thereof.
[0026] Any useful thermosetting liquid silicone rubber or material can be utilized to form
the silicone sealing element
23. Liquid silicone rubber is a high purity platinum cured silicone with low compression
set, great stability and ability to resist extreme temperatures of heat and cold.
Due to the thermosetting nature of the material, liquid silicone injection molding
often requires special treatment, such as intensive distributive mixing, while maintaining
the material cool before it is pushed into the heated cavity and vulcanized. Silicone
rubber is a family of thermoset elastomerics that have a backbone of alternating silicone
and oxygen atoms and methyl or vinyl side groups. Silicone rubbers maintain their
mechanical properties over a wide range of temperatures and the presence of methyl-groups
in silicone rubbers makes these materials hydrophobic.
[0027] Illustrative thermosetting silicone material includes self-adhesive liquid silicone
rubbers available under the trade designation: ELASTOSIL LR 3070 from Wacker-Silicones,
Munich, Germany; the KE2095 or KE2009 series (such as, for example, KE2095-60, KE2095-50,
KE2095-40) or X-34-1547A/B, X-34-1625A/B, X-34-1625A/B all from Shin-Etsu Chemical
Co., LTD., Japan. These self-adhesive liquid silicone rubbers do not require pretreatment
of certain thermoplastic surfaces for the liquid silicone rubbers to chemically bond
to the thermoplastic surface.
[0028] In the illustrated embodiment, the first surface
21 and second surface
22 are opposing major surfaces. One or more apertures
24 extend through the respirator attachment component body thickness defined between
the opposing first surface
21 and second surface
22. During the overmolding manufacture of the respirator attachment component, liquid
silicone (that forms the silicone sealing element
23) flows through the one or more apertures
24 and forms a mechanical interlock between the silicone sealing element
23 and the rigid respirator attachment body portion
20.
[0029] A diaphragm
25 can be fixed to me respirator attachment body portion
20. This diaphragm
25 is biased against the respirator attachment body portion
20 to allow unidirectional air flow through the respirator attachment body portion
20.
[0030] The respirator attachment body portion
20 can also include a bayonet attachment element
26. The bayonet attachment element
26 assists in fastening the respirator attachment body portion
20 to the cheek opening
12 of the respiratory protection mask
10. The bayonet attachment element
26 mates with a complementary element within or adjacent to the cheek opening
12 of the respiratory protection mask
10. This bayonet attachment system secures the illustrated inhalation valve
18 to the cheek opening
12 of the respiratory protection mask
10.
[0031] When assembled, the silicone sealing element
23 of the illustrated inhalation valve
18 is disposed between the first surface
21 and the adjacent cheek opening
12 surface, forming an air-tight seal at the sealing element surface and cheek opening
surface interface. The term "air-tight seal" refers to a connection that substantially
prevents unfiltered or ambient air from entering an interior portion of the respiratory
protection composite facepiece
11 at the connection interface.
[0032] Air-tightness is measured with a vacuum leak test. The test fixture consists of a
sealed chamber with three ports. The volume of the chamber is approximately 750 cm
3. A respirator attachment component is affixed to one of the three ports by means
of its bayonet attachment element. A vacuum gauge capable of measuring the pressure
differential between the inside of the chamber and the ambient air (to at least 25
cm water) is attached to a second port on the fixture. A vacuum source is attached
to the third port through a shut off valve. To conduct the test, the shut-off valve
is opened and the vacuum source is turned on to evacuate the chamber to a pressure
of 25 cm water below atmospheric pressure (as indicated by the vacuum gauge). The
shut-off valve is then closed and the vacuum source is turned off. The vacuum level
inside the chamber is monitored for 60 seconds. Inward leakage of air causes the pressure
inside the chamber to increase, thereby reducing the vacuum level. For the current
disclosure, the pressure differential between the chamber and the ambient air is greater
than 15 cm of water after 60 seconds, More preferably, the pressure differential remains
above 24 cm or water after 60 seconds.
[0033] The silicone sealing element
23 of the illustrated inhalation valve
18 is also disposed between the second surface
22 and an attached filtered air source element (not shown). The filtered air source
element can be a chemical or particulate filtration cartridge or a clean air supply
source. The filtered air source element can be attached to the illustrated inhalation
valve
18 via a bayonet attachment element
27 on the respirator attachment body portion
20. This bayonet attachment element
27 mates with a complementary element on the filtered air source element. Thus, the
silicone sealing element
23 of the illustrated inhalation valve
18 forms an air-tight seal at the sealing element surface and filtered air source element
interface.
[0034] FIG. 5 is a perspective view of an illustrative exhalation valve
16 without showing the diaphragm
35 (shown in
FIG. 2).
FIG. 6 is a cross-section perspective view of the exhalation valve
16 illustrated in
FIG. 5. The exhalation valve
16 includes a polymeric rigid respirator attachment body portion
30 having a first surface
31 and a second surface
32. A silicone sealing element
33 is chemically bonded to the first surface
31.
[0035] The silicone sealing element
33 can be formed by overmolding a thermosetting silicone material onto a thermoplastic
polymeric rigid respirator attachment body portion
30. The thermosetting silicone material chemically bonds (i.e., adhesive bonding or
covalent bonding) directly onto to the thermoplastic polymeric rigid respirator attachment
body portion
30 first surface
31. The terms "chemical bonding or chemically bonded" are described above.
[0036] The thermoplastic polymeric rigid respirator attachment body portion
30 can be formed of any useful thermoplastic material, as described above. Any useful
thermosetting liquid silicone rubber or material can be utilized to form the silicone
sealing element
33, as described above.
[0037] In the illustrated embodiment, the first surface
31 and second surface
32 are opposing major surfaces. In some embodiments, one or more apertures (not shown)
extend through the respirator attachment component body thickness defined between
the opposing first surface
31 and second surface
32. During the overmolding manufacture of the respirator attachment component, liquid
silicone (that forms the silicone sealing element) flows through the one or more apertures
and forms a mechanical interlock between the silicone sealing element and the rigid
respirator attachment body portion.
[0038] A diaphragm
35 can be fixed to the respirator attachment body portion
30 (see
FIG. 2). This diaphragm
35 is biased against the respirator attachment body portion
30 to allow unidirectional air flow through the respirator attachment body portion
30.
[0039] The respirator attachment body portion
30 can also include a bayonet attachment element
36. The bayonet attachment element
36 assists in fastening the respirator attachment body portion
30 to the nasal opening
13 of the respiratory protection mask
10. The bayonet attachment element
36 mates with a complementary element within or adjacent to the nasal opening
13 of the respiratory protection mask
10. This bayonet attachment system secures the illustrated exhalation valve
16 to the nasal opening
13 of the respiratory protection mask
10.
[0040] When assembled, the silicone sealing element
33 of the illustrated exhalation valve
16 is disposed between the first surface
31 and the adjacent nasal opening
13 surface, forming an air-tight seal at the sealing element surface and nasal opening
surface interface. The term "air-tight seal" is defined above.
[0041] FIG. 7 is a perspective view of an illustrative speaking diaphragm
14, and
FIG. 8 is a cross-section perspective view of the speaking diaphragm
14 illustrated in
FIG. 7. The speaking diaphragm
14 includes a polymeric rigid respirator attachment body portion
40 having a first surface
41 and a second surface
42. A silicone sealing element
43 is chemically bonded to the first surface
41. A diaphragm
45 is fixed to the polymeric rigid respirator attachment body portion
40. The diaphragm
45 assists in the transmission of sound from a user of the respirator
10 to another person.
[0042] The silicone sealing element
43 can be formed by overmolding a thermosetting silicone material onto a thermoplastic
polymeric rigid respirator attachment body portion
40. The thermosetting silicone material chemically bonds (i.e., adhesive bonding or
covalent bonding) directly onto to the thermoplastic polymeric rigid respirator attachment
body portion
40 first surface
41. The terms chemical bonding or chemically bonded are described above.
[0043] The thermoplastic polymeric rigid respirator attachment body portion
40 can be formed of any useful thermoplastic material, as described above. Any useful
thermosetting liquid silicone rubber or material can be utilized to form the silicone
sealing element
43, as described above.
[0044] In the illustrated embodiment, the first surface
41 and second surface
42 are opposing major surfaces. In some embodiments, one or more apertures (not shown)
extend through the respirator attachment component body thickness defined between
the opposing first surface
41 and second surface
42. During the overmolding manufacture of the respirator attachment component, liquid
silicone (that forms the silicone sealing element) flows through the one or more apertures
and forms a mechanical interlock between the silicone sealing element and the rigid
respirator attachment body portion.
[0045] The respirator attachment body portion
40 can also include a bayonet attachment element
46. The bayonet attachment element
46 assists in fastening the respirator attachment body portion
40 to the nasal opening
13 of the respiratory protection mask
10. The bayonet attachment element
46 mates with a complementary element within or adjacent to the nasal opening
13 of the respiratory protection mask
10. This bayonet attachment system secures the illustrated speaking diaphragm
14 to the nasal opening
13 of the respiratory protection mask
10.
[0046] When assembled, the silicone sealing element
43 of the illustrated speaking diaphragm
14 is disposed between the first surface
41 and the adjacent nasal opening
13 surface, forming an air-tight seal at the sealing element surface and nasal opening
surface interface. The term "air-tight seal" is defined above.
EXAMPLES
[0047] Several tests were used to identify suitable combinations of silicone rubbers and
thermoplastic materials. Of particular interest is the strength of the bond between
the silicone rubber and thermoplastic material, which affects the durability of the
air-tight seal.
[0048] A surrogate test strip was developed to permit measurement of the bond strength.
The test strip is prepared by molding a rigid, flat substrate piece 51 mm long, 25
mm wide, and 2 mm thick with thermoplastic material. The substrate is then clamped
into a second mold such that 6 mm of one end of the substrate protrudes into the cavity
of the second mold. The cavity of the second mold is 27 mm wide and 49 mm long. The
depth of the mold is 2 mm, expanding to 4 mm in the immediate vicinity of the protruding
substrate end, such that when silicone is injected into the mold cavity it forms a
layer 1 mm thick on all sides of the protruding substrate end. The resulting test
strip is thus 94 mm long, with a rigid thermoplastic substrate piece on one end and
silicone rubber on the other end.
[0049] The strength of the bond between the substrate material and silicone is measured
by gripping the two ends of the test strip in the jaws of a mechanical tester such
as an MTS Model 858 Material Test System (MTS Systems Corporation, Eden Prairie, MN),
stretching it until the test strip breaks apart, and recording the force at which
failure occurs. Examples of the force to failure are shown in Table 1. Examples 1
through 4 show that bond strengths greater than 300 N can be achieved with the appropriate
combination of materials. For Comparative Examples C1 and C2, the silicone did not
bond to the thermoplastic material.
| Example |
Silicone |
Thermoplastic Substrate |
Average Force to Failure (N) |
| 1 |
Shin-Etsu KE2095-60 |
RTP Nylon 6/6 |
136 |
| 2 |
Wacker 3070-60 |
RTP Nylon 6/6 |
303 |
| 3 |
Dow LC-70-2004 |
Zytel PA |
174 |
| 4 |
Wacker 3070-60 |
Zytel PA |
166 |
| C1 |
Dow LC-70-2004 |
RTP Nylon 6/6 |
No bonding |
| C2 |
Shin-Etsu KE2095-60 |
Zytel PA |
No bonding |
[0050] Dow LC-70-2004 silicone is produced by Dow Corning Corporation, Midland MI; RTP Nylon
6/6 is a polyamide produced by RTP Company, Winona, MN; Zytel PA is a polyamide produced
by E.I. du Pont de Nemours, Wilmington, DE.
[0051] Thus, embodiments of the RESPIRATOR ATTACHMENT COMPONENT WITH MOLDED THERMOSET ELASTOMERIC
SEAL are disclosed. One skilled in the art will appreciate that the present invention
can be practiced with embodiments other than those disclosed. The disclosed embodiments
are presented for purposes of illustration and not limitation, and the present invention
is limited only by the claims that follow.